Doped Multiple Nanoparticles with Hydroxyapatite Coating Show Diverse Health Effects in vivo

Xinlin Li,1,2,* Baojuan Yang,3,4,* Mengfei Xu,1,2 Fangyi Li,3,4 Zhaoli Geng,1,2 Weiqiang Cui,3,4 Xingfu Sun,3,4 Yanle Li,3,4 Yi Liu1,2 1Department of Orthodontics, School and Hospital of Stomatology, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, People’s Republic of China; 2Shandong Key Laboratory of Oral Tissue Regeneration, Shandong Engineering Laboratory for Dental Materials and Oral Tissue Regeneration, Shandong Provincial Clinical Research Center for Oral Diseases, Jinan, Shandong, 250012, People’s Republic of China; 3Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education, School of Mechanical Engineering, Shandong University, Jinan, 250061, People’s Republic of China; 4National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan, 250061, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yi Liu, Department of Orthodontics, School and Hospital of Stomatology, Cheeloo College of Medicine, Shandong University, No. 44-1 Wenhua Road West, Jinan, Shandong, 250012, People’s Republic of China, Tel +86-531-88381630, Email yiliu@sdu.edu.cn Yanle Li, Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education, Shandong University School of Mechanical Engineering, No. 17923, Jingshi Road, Jinan, 250061, People’s Republic of China, Tel +86-531-88392208, Email yanle.li@sdu.edu.cnIntroduction: The lack of osteoinductive, angiogenic and antimicrobial properties of hydroxyapatite coatings (HA) on titanium surfaces severely limits their use in orthopedic and dental implants. Therefore, we doped SiO2, Gd2O3 and CeO2 nanoparticles into HA to fabricate a HASiGdCe coating with a combination of decent antibacterial, angiogenic and osteogenic properties by the plasma spraying technique.Methods: The HASiGdCe coating was analyzed by SEM (EDS), surface roughness tests, contact angle tests, XRD, FTIR spectroscopy, tensile tests and electrochemical dynamic polarization tests. Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (PAO-1) were used as representative bacteria to verify the antibacterial properties of the HASiGdCe coating. We evaluated the cytocompatibility and in vitro osteoinductivity of the HASiGdCe coating by investigating its effect on the cell viability and osteogenic differentiation of MC3T3-E1 cells. We assessed the in vitro angiogenic activity of the HASiGdCe coating by migration assay, tube formation assay, and RT‒PCR analysis of angiogenic genes in HUVECs. Finally, we used infected animal femur models to investigate the biosafety, antimicrobial and osteointegration properties of the HASiGdCe coating in vivo.Results: Through various characterization experiments, we demonstrated that the HASiGdCe coating has suitable microscopic morphology, physical phase characteristics, bonding strength and bioactivity to meet the coating criteria for orthopedic implants. The HASiGdCe coating can release Gd3+ and Ce4+, showing strong antibacterial properties against MRSA and PAO-1. The HASiGdCe coating has been shown to have superior osteogenic and angiogenic properties compared to the HA coating in in vitro cellular experiments. Animal implantation experiments have shown that the HASiGdCe coating also has excellent biosafety, antimicrobial and osteogenic properties in vivo.Conclusion: The HASiGdCe coating confers excellent antibacterial, angiogenic and osteogenic properties on titanium implants, which can effectively enhance implant osseointegration and prevent bacterial infections, and it accordingly has promising applications in the treatment of bone defects related to orthopedic and dental sciences.Graphical Abstract: Keywords: hydroxyapatite coatings, SiO2, Gd2O3, CeO2, osseointegration, antibacterial